Movable chromatic corrector.



W. H. KUNZ.

MOVABLE CHROMATIC CORRECTOR. APPLICATION FILED ocT.22.1914.

1,175,961. PatentedMar. 21,1916.

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1 haven-lg?, 'VilliamHl-funzj images by red WILLIAM-H.- KUNZ, OF BOSTON, MASSA CHUSMETTS, ASSIGNR T0 KUN'Z-GARNISS COMPANY, A C ORPORA'1ION- 0F MASSACHUSETTS'.

Specification of Letters Patent.

MovABLE cHRoMA'rIc Comoros.

Patented Mar. 21, 1916.

Application inea octoter 22, 1914. serial No. 868,133.

To all whom t may concern Be it known that I, WILLIAM H. KUNz, a citizen of the United States, and a resident of the city of Boston, in the county of Suffolk and Commonwealth of Massachusetts, have invented certain new and useful Improvements in Movable Chromatic Correctors, lof which the following is a full, clear, and exact specification.

This invention relates to that method lvof taking and projecting Vmoving pictures in two colors, wherein alternate pictures are taken through alternating color-filters, and are thrown upon the screen through similarly alternating color-lilters. In otherv words, one photograph on the film is taken through a green filter, the second through a red color lter, the nextthrough the green ter again, and so on alternating` throughout the length of the film. In the same manner, the projection is made through similarly alternatin green and red color filters, so that the e ect upon the screen is a moving picture substantially in the colors of nature.

Because. of the increased light-absorption caused by the passage of the light through the color-filters, and for other reasons,- twocolor pictures require from iifteen to thirty tunes as much light as ordinary black and.

white pictures, thus necessitating extremely high speed lenses. Such extreme speed lenses have not yet been made that will form and of the same size, an it has heretofore been necessary to use the slower lenses which can be corrected to prevent color-refraction. It is the purpose of this invention to provideA a means of overcoming this chromatic defect in the fast lenses and thus permitting their use in color work.

A further object is the construction of means for adjustable varying and equalizing the amounts of lights through the two co or-lters ,in order to make up for the lesser actinic power fof the rays passing through one color-filter as compared with the rays through the other lter.

For the accomplishment ofthe first of the two purposes, I provide means for the momentary introduction in the path of one of the sets of rays of a sheet of transparent material sufficient in thickness to prolong their focusing to the same plane as that on which the other light, rays lrotary shutter and 3, with a film Cgireen light that will be justalole shutter in order vide two segmental plates .6

While there are several Vways in which this can be done, it is preferable to mount such transparent material in one segment of the have the shutter-segments compose the two color-filters. Such transparent material is usually disposed 0n the green color-filter since the rays through green are the ones which usually fall short of focusing upon the film which has been focused for the red rays.

Referring to the drawings forming part of this specification, Figure l is a face view of a combinedrotary shutter and color filter embodying my improvements. Fig. 2 is a sectional view thereof on the dotted line X in Fig. 1. Fig. 43 is a face view of one of the members composing the adjustable element of the-shutter.

It is found that a color filtergis best produced by cementing a film of colored gelatin between two sheets of glass either clear or partially stained, but preferably clear. I therefore cement to one surface of a circular sheet of glass 1 two glass segments 2 of green gelatin 5 between the segment 3 and the circular sheet, and a film of red gelatin between the segment 2 and the sheet l( s-shown in Fig. 2, the glass segment 2 is made materially thickerfthan the segment 3, suiiiciently so to lengthen out the focal length of the rays of one color to equal that of the other rays. Consequently, as the shutter rotates between the lens and the film in the lproduction of the photographs, or between the projecting j in displaying the moving pictures, every time the green color lter passes the lens the eXtra thick segment 2 elongates the focusing length to accord with that given by the thin segment 3 to the red rays.

Since in the production as well as in the projection of nlm-pictures it is necessary to have the light cut off during the shiftings of the film, it is customary to provide a rotary shutter having alternating opaque and transparent segments. For color work I have found it' essential to provide an adto compensate for the unequal actinic effect of the color filters; the rays of one color'` being generally stronger in their action on the sensitive film than the other rays. In doin this, I prousually employed, and to' lens and the screen Fig. 3) each 110 'Y approximately counterbalancing arm 10. All of these segmental plates are clamped in place upon'the spindle 11 by a nutlQ pressing them against the shoulder 13.

. To protect the glass plates from injury and especially. from becoming loosened from the films and flying 0H, they are surrounded by a metal rim '14 embracing their edges, as

shown in Fig. 2; and to counterbalance the thicker segment the rim is supplied with a counterweight 15. Thus made, a rotary shutter is produced which not only regulates the amount of light permitted to pass through the color filters to equalize the lighteffects upon the sensitive lm or onthe eye of the observer, but which causes the focusing of the sets of colored rays to accurately correspond, thereby rendering the definition.

and sharpness of the pictures, both as photographed and projected, to be practically perfect.

While I have described my improvements as applied for two-color work, they may I 'equally Well be employed for more complete color rendering wherein a larger number of different,v color filters are used.

.What I claim is:

l. A motion Apicture device comprising means including color filters for successively `directing a plurality of differently colored sets of light rays, and means for periodi- \cally operating to increase the focal length of the set. of colored rays which is normally shorter than that of the others, the lastnamed means consisting of transparent plates of different thicknesses, the thicker plate being located `over the color filter which allows rays of shorter focal length to pass and being of proper thickness to compensate for the shorter focal length of these rays. v

2. A motionI picture device comprising means for successively directing a plurality of differently colored sets of light rays, and Aa transparent plate adapted to vbe periodically introduced into the path of the rays having normally a shorter focal length than the remainder, said plate being of proper thickness to compensate for the shorter focal length of the rays passing through it.

3. A motion picture device comprising means for successively directing aV plurality of differently colored sets of light rays, and two glass plates ofv different thicknesses adapted to be alternately-moved into and out ofthe path of the rays, the glass plate of greater thickness being locatedV in the path of thev rays-of shorter focal length and the last-mentioned plate being of a proper I thickness to compensate for'the shorter focal length of the rays passing through it.

4. A motion picture device .comprising means for successively introducting two differentcolor filters into the path of lightrays, andv means for synchronously. introducing into and withdrawing from said path a sheet of glass the thickness of which is proportioned for suitably lengthening the filter allowing rays of shorter` focallength to pass.

5. A motion picture device comprising a each other in colors, and means for rotating the shutter, a vgreater thickness of glass being provided for the color filter allowing of shorter focal length to pass, than for the other color lter such thickness being made suiiicient-to compensate for the Vshorter focal ,length of the rays passing through it. f'

' focallength of the rays throughthe color- 'shutter carrying ,color filters differing from f 6. A motion picture device comprising a circular memberfand means for rotating it, said member. having aplurality vofcolor filters and a plurality .of glass sections of diierent thicknesses, the thickest section of glass being located over the color filter which allows rays of a shorter focal length to pass, the last-mentioned section being made of a proper thickness to compensate for the shorter focal length of the rays 'passing through it.

7. A motionpicture device comprising a glass disk, two glass segments of different thicknesses, films of different colorsbeing cemented between the segments and disk,

v the film allowing rays of shorter focal length to pass being between the disk and the thicker segment, said device having means for rotating it, the last-mentioned segment being of a proper thickness to compensate for the shorter focal length of the rays pass'- ing through it.

8. A motion picture device comprising a circular member and means for rotating it, saidmember having a plurality of color filters and a plurality of glass sections of different thicknesses, 'the thickest section of glass being located over the color Vfilter which allows rays of a shorter focal length to pass, and a counterweight for the thicker sections, the thicker sections of glass being of a proper thiclmess to compensate for the shorter focall length of the rays passing through them. 9. A motion picture device'comprising a circular glass disk, means for rotating it, glass sections cemented thereto, colorflters between said disk and sections,- the glass section,` whose colorlter allows rays of shorter focal length to pass, being thicker than the others, a metal rim encircling said disk and sections and adapted for counterbalancing the thicker glass section, the latter being of proper thickness to compensate for the shorter focal length of the rays passing through it.

10. A motion picture device comprising a glass disk and means for its rotation, glass segment of different thicknesses, films of differently colored gelatin cemented between said disk and segments, the segment of greater thickness being located over the color filter which allows rays of shorter focal length to pass and being of a proper thickness to compensate for theirV shorter focal length, a metal rim encircling said disk and segments, and a counterweight car- WILLIAM H. KUN Z. Witnesses A A. B. UPHAM, A. S. MOFFAT. 

